Make some GMs animate

gm/dashcircle.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkPath.h"
 #include "SkDashPathEffect.h"
 
 int dash1[] = { 1, 1 };
 int dash2[] = { 1, 3 };
 int dash3[] = { 1, 1, 3, 3 };
 int dash4[] = { 1, 3, 2, 4 };
 
 struct DashExample {
     int* pattern;
     int length;
 } dashExamples[] = {
     { dash1, SK_ARRAY_COUNT(dash1) },
     { dash2, SK_ARRAY_COUNT(dash2) },
     { dash3, SK_ARRAY_COUNT(dash3) },
     { dash4, SK_ARRAY_COUNT(dash4) }
 };
 
-DEF_SIMPLE_GM(dashcircle, canvas, 900, 1200) {
-    SkPaint refPaint;
-    refPaint.setAntiAlias(true);
-    refPaint.setColor(0xFFbf3f7f);
-    refPaint.setStyle(SkPaint::kStroke_Style);
-    refPaint.setStrokeWidth(1);
-    const SkScalar radius = 125;
-    SkRect oval = SkRect::MakeLTRB(-radius - 20, -radius - 20, radius + 20, radius + 20);
-    SkPath circle;
-    circle.addCircle(0, 0, radius);
-    SkScalar circumference = radius * SK_ScalarPI * 2;
-    int wedges[] = { 6, 12, 36 };
-    canvas->translate(radius + 20, radius + 20);
-    for (int wedge : wedges) {
-        SkScalar arcLength = 360.f / wedge;
-        canvas->save();
-        for (const DashExample& dashExample : dashExamples) {
-            SkPath refPath;
-            int dashUnits = 0;
-            for (int index = 0; index < dashExample.length; ++index) {
-                dashUnits += dashExample.pattern[index];
+
+class DashCircleGM : public skiagm::GM {
+public:
+    DashCircleGM() : fRotation(0) { }
+
+protected:
+    SkString onShortName() override { return SkString("dashcircle"); }
+
+    SkISize onISize() override { return SkISize::Make(900, 1200); }
+
+    void onDraw(SkCanvas* canvas) override {
+        SkPaint refPaint;
+        refPaint.setAntiAlias(true);
+        refPaint.setColor(0xFFbf3f7f);
+        refPaint.setStyle(SkPaint::kStroke_Style);
+        refPaint.setStrokeWidth(1);
+        const SkScalar radius = 125;
+        SkRect oval = SkRect::MakeLTRB(-radius - 20, -radius - 20, radius + 20, radius + 20);
+        SkPath circle;
+        circle.addCircle(0, 0, radius);
+        SkScalar circumference = radius * SK_ScalarPI * 2;
+        int wedges[] = { 6, 12, 36 };
+        canvas->translate(radius+20, radius+20);
+        for (int wedge : wedges) {
+            SkScalar arcLength = 360.f / wedge;
+            canvas->save();
+            for (const DashExample& dashExample : dashExamples) {
+                SkPath refPath;
+                int dashUnits = 0;
+                for (int index = 0; index < dashExample.length; ++index) {
+                    dashUnits += dashExample.pattern[index];
+                }
+                SkScalar unitLength = arcLength / dashUnits;
+                SkScalar angle = 0;
+                for (int index = 0; index < wedge; ++index) {
+                    for (int i2 = 0; i2 < dashExample.length; i2 += 2) {
+                        SkScalar span = dashExample.pattern[i2] * unitLength;
+                        refPath.moveTo(0, 0);
+                        refPath.arcTo(oval, angle, span, false);
+                        refPath.close();
+                        angle += span + (dashExample.pattern[i2 + 1]) * unitLength;
+                    }
+                }
+                canvas->save();
+                canvas->rotate(SkIntToScalar(fRotation));
+                canvas->drawPath(refPath, refPaint);
+                canvas->restore();
+                SkPaint p;
+                p.setAntiAlias(true);
+                p.setStyle(SkPaint::kStroke_Style);
+                p.setStrokeWidth(10);
+                SkScalar intervals[4];
+                int intervalCount = dashExample.length;
+                SkScalar dashLength = circumference / wedge / dashUnits;
+                for (int index = 0; index < dashExample.length; ++index) {
+                    intervals[index] = dashExample.pattern[index] * dashLength;
+                }
+                p.setPathEffect(SkDashPathEffect::Make(intervals, intervalCount, 0));
+                canvas->save();
+                canvas->rotate(SkIntToScalar(fRotation));
+                canvas->drawPath(circle, p);
+                canvas->restore();
+                canvas->translate(0, radius * 2 + 50);
             }
-            SkScalar unitLength = arcLength / dashUnits;
-            SkScalar angle = 0;
-            for (int index = 0; index < wedge; ++index) {
-                for (int i2 = 0; i2 < dashExample.length; i2 += 2) {
-                    SkScalar span = dashExample.pattern[i2] * unitLength;
-                    refPath.moveTo(0, 0);
-                    refPath.arcTo(oval, angle, span, false);
-                    refPath.close();
-                    angle += span + (dashExample.pattern[i2 + 1]) * unitLength;
-                }
-            }
-            canvas->drawPath(refPath, refPaint);
-            SkPaint p;
-            p.setAntiAlias(true);
-            p.setStyle(SkPaint::kStroke_Style);
-            p.setStrokeWidth(10);
-            SkScalar intervals[4];
-            int intervalCount = dashExample.length;
-            SkScalar dashLength = circumference / wedge / dashUnits;
-            for (int index = 0; index < dashExample.length; ++index) {
-                intervals[index] = dashExample.pattern[index] * dashLength;
-            }
-            p.setPathEffect(SkDashPathEffect::Make(intervals, intervalCount, 0));
-            canvas->drawPath(circle, p);
-            canvas->translate(0, radius * 2 + 50);
+            canvas->restore();
+            canvas->translate(radius * 2 + 50, 0);
         }
-        canvas->restore();
-        canvas->translate(radius * 2  + 50, 0);
     }
-}
+
+    bool onAnimate(const SkAnimTimer& timer) override {
+        fRotation = (fRotation + 2) % 360;

[jvanverth1, 2016/04/08 19:10:56]

I suppose it's not a big deal, but the animation speed of this will vary
depending on the frame rate.

[robertphillips, 2016/04/08 20:14:58]

Doh - fixed.

+        return true;
+    }
+
+private:
+    int fRotation;
+
+    typedef GM INHERITED;
+};
+
+DEF_GM(return new DashCircleGM; )